The invention relates to pressurized packaging and methods of assembling and filling pressurized packages, e.g. in the field of so-called aerosol dispensers.
At the present time a large number of aerosol dispensers are manufactured and filled by the following established method. A valve is constructed from two plastics pieces, a rubber gasket, a spring and a so-called one-inch (approximately 25 mm) diameter plated metal cup. At the centre of the cup, there is an upstanding neck with a turned-over edge and the plastics pieces, the gasket and the spring are assembled in the neck which is then deformed to retain these parts in sealing engagement to form an operable, normally-closed, valve mechanism. A plastics dip-tube is attached to the inlet end of the mechanism and a gasket is inserted in a turned rim of the cup.
The container for this valve has a one inch (about 25 mm) aperture in one metal end wall and is firstly charged through the aperture with a predetermined amount of the material to be dispensed. The valve with its cup is then located in alignment with the container aperture and a filling apparatus head is placed in sealing contact with the apertured end wall of the container. The container is then purged through its aperture and via the head, after which propellant under pressure is introduced by the head around the cup and through the aperture. When a measured amount of propellant has been supplied, the cup is brought into engagement with the aperture and sealed thereto by a collet in the head deforming the cup wall radially outwardly to hold the gasket in the cup rim against the turned over rim of the aperture.
However, this construction and method of charging are by no means ideal from the point of view of cost and leakage. Cost-wise, this conventional method is not ideal because of the large number of parts involved and also because of the not insignificant wastage of propellant left in the cup and in the head cavity, which must of course have a large enough capacity to embrace the collet and the relatively large container aperture. Leakage is a problem because of:
A. the possibility of leakage between the gasket and the plastics parts of the valve; PA1 b. the leakage path between the cup neck and the valve parts; and PA1 c. the large leakage path at the periphery of the cup.
The latter path, as will be apparent, is so constructed that the pressure in the container itself acts to oppose the seal at that path. Moreover, the depth of the rim of the aperture is only about one eighth of an inch (about 3 mm) so that the depth of the seal is relatively small in comparison with the path length of about 3.1 inches (80 mm). Also it is seen that this path is sealed under conditions which are not ideal, i.e. by a collet constrained within the confines of the filling head and needing to operate quickly and efficiently subsequent to the filling with propellant. Moreover, during filling, the rim gasket temperature falls considerably and this can cause the gasket to be detached from its required position. If the charged container is found to be faulty in any respect, normally the complete product must be rejected.
Another method used at the present time uses the same plurality of parts which are completely assembled, with a nozzle, before the propellant is introduced. In this case filling occurs by displacing the nozzle into sealing engagement with the neck of the metal cup and forcing propellant through two holes in the nozzle into the annular gap between the neck and the valve stem. The propellant displaces the gasket from its sealing position to permit the propellant to enter the container. This method, of course, requires a multipart valve structure.
I have already proposed some improvement in U.S. Pat. No. 3,598,324 and No. 3,620,421. In those cases I propose a valve comprising a unitary member having a tubular body portion containing a valve inlet passage, a valve actuating portion defining a valve outlet passage. The controllable flow path of the valve is wholly within the unitary member and has an annular valve seat within the member. In one case the valve seat is engaged by a resilient gasket engaged within an annular cavity of the body portion. A flexible annular wall portion integrally seals the body portion to the actuating portion to allow deflection of the actuating portion relative to the body portion. There is accordingly no leakage path to the outside at a point intermediate the inlet and outlet so that the leakage noted above at (a) is eliminated.
It is an object of the invention to provide improved packaging which according to one aspect of the invention involves an improved method of making a pressurized package which method according to the aforementioned U.S. Pat. No. 3,620,421 includes the steps of: providing a valve comprising a unitary member having a tubular body portion of compressible material containing a valve inlet passage and an actuating portion containing a valve outlet passage, the inlet and outlet of the valve being joined by a controllable flow path extending wholly within the unitary member and incorporating an annular valve seat spaced from the inlet of the valve; providing a container having an aperture defined by a container neck; and sealing the valve member in the neck.